Vascular/venous access devices for introducing catheters into a patient's vascular system are well known. The simplest of such devices comprises a through-the-needle catheter having a cannula which generally comprises a metal needle inserted into the patient's vein and through which a catheter may subsequently be introduced. A common problem associated with the use of such prior art through-the-needle catheter systems arises in removing the cannula after the catheter has been introduced into the vein. Since the cannula is typically comprised of a rigid metal needle, it is desirable to remove the cannula from the patient's vein after insertion of the catheter to prevent trauma to the vein caused by the cannula's rigid structure and/or sharp tip. However, once the catheter has been inserted into the vein, the cannula can typically only be removed by retracting the same upwardly along the catheter, thereby exposing the patient as well as administering personnel to accidental contact with the cannula.
In recognizing the discomfort and extraction problems of the cannula associated with through the needle catheter systems, over-the-needle catheter systems have been widely utilized for venous access applications. In such over-the-needle catheter systems, a thin catheter having a hub at its proximal end is placed over a rigid cannula, such as a needle, whereby the cannula as well as the catheter may be simultaneously inserted into the vein of a patient. Once the cannula and catheter and have been introduced into the vein, the cannula may be withdrawn from the interior of the catheter leaving the catheter disposed within the patient's vein. Subsequently, required administration line communication can be effectuated with the catheter by interconnection with its hub mounted to the proximal end of the catheter. However, due to such over-the-needle catheters being inserted into the vein of the patient concurrently with the rigid cannula, such over-the-needle catheters must possess sufficient rigidity to prevent the same from traveling axially upward relative to the cannula during the insertion process. As such, over-the-needle catheters are limited in their axial length and are incapable of being inserted upwardly through the length of the vein or artery without causing trauma and/or puncture to the vein.
In recent years, the desirability of utilizing a peripherally inserted central catheter (PICC) line into a patient for medical applications has become widespread. In such PICC line applications, a flexible catheter must be introduced into the vascular system of a patient and subsequently be manipulated to allow the catheter to wind its way upwardly through the vascular system to a desired location. Due to the requirement of advancing the catheter upwardly through the vascular system, the catheter must be formed from a soft, biocompatible, pliable, and flexible material which is capable of winding through and extending through substantial axial lengths of the vascular system, i.e. from two to thirty inches or more, without causing trauma to the vascular system or puncturing therethrough. In view of such requirements, heretofore, through-the-needle catheter systems have been typically utilized wherein after venous insertion, the cannula is retained within the patient and the desired length of catheter is inserted through the cannula and into the vein of the patient. In such applications blood leakage is commonplace, thus exposing administering personnel to substantial health risks, such as those associated with the AIDS virus, hepatitis, and other infectious diseases.
In view of these concerns, recently an over-the-needle catheter system has been introduced specifically adapted for PICC line applications which attempts to minimize accidental exposure of medical personnel to patient's blood. This particular venous access device is manufactured by Menlo Care, Inc. of Palo Alto, Calif. and is marketed under the trademark LANDMARK venous access device.
The LANDMARK venous access device facilitates the insertion of a limited length (i.e. finite length) of catheter into a patient's vein while permitting the needle to be withdrawn after the initial insertion via a stylet extending through the catheter and then stowed within a protective sheath to prevent accidental puncture and/or exposure. However, the LANDMARK venous access device is strictly limited in the length of the catheter provided, thus necessitating the correct initial selection of catheter length. Additionally, the LANDMARK venous access device is relatively complex in its construction, thus increasing the cost of fabrication and consequently increasing its associated patient cost. Furthermore, the LANDMARK venous access device is relatively complicated to use, requiring a significant amount of training and manipulative skill.
In view of the shortcomings of the prior art, it is desirable to provide an improved vascular/venous access device which would permit the introduction of an unlimited length of catheter into a patient's vascular system which facilitates removal of the needle to prevent accidental punctures and/or exposure; which is simple and inexpensive to fabricate; and which requires a minimum of training and manipulative skill to practice.